[kwlug-disc] MDADM and RAID

Chris Irwin chris at chrisirwin.ca
Wed Mar 3 14:06:44 EST 2010


On Wed, Mar 3, 2010 at 13:46, Rashkae <rashkae at tigershaunt.com> wrote:
> John Van Ostrand wrote:
>>
>> ----- "Rashkae" <rashkae at tigershaunt.com> wrote:
>>>
>>> John Van Ostrand wrote:
>>>
>>>> Those same disks as RAID0+1:
>>>>
>>>>        md0 : active raid0 sde1[3] sdd1[2] sdc1[1] sdb1[0]
>>>>              286727680 blocks 64k chunks
>>>
>>> Where do you get the +1 from? All I see here is a single Raid 0 array,
>>>
> That much I understand, the part that I don't understand is:
>
> md0 : active raid0 sde1[3] sdd1[2] sdc1[1] sdb1[0]
>
> I would have expected something like:
>
> md0: active raid1 sde1 add1
> md1: active raid1 sdc1 sdb1
> md2: active raid0 md1 md2
>
> I've never actually created a 0+1 or 1+0 array, but it seems odd to me that
> it would appear to be a single raid0 array in the mdstat.

I'm now doing testing according to John's methodology with some
different array types. Right now I'm waiting for my RAID10 array to
sync. But for me, RAID10 shows as RAID10. Unless John manually stacked
arrays (as you were expecting) and snipped the output.

md1 : active raid10 sdd2[3] sdc2[2] sdb2[1] sda2[0]
      975739392 blocks 256K chunks 2 near-copies [4/4] [UUUU]

Each sync takes about 1.5 hours, so I won't be posting my results until later.

-- 
Chris Irwin
<chris at chrisirwin.ca>



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